using System;
using System.Collections.Generic;
using System.ComponentModel.Composition;
using System.Diagnostics;
using System.Diagnostics.Contracts;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Pithos.Interfaces;
using Pithos.Network;
using log4net;

namespace Pithos.Core.Agents
{
    [Export]
    public class WorkflowAgent
    {
        Agent<WorkflowState> _agent;
                
        public IStatusNotification StatusNotification { get; set; }
        [Import]
        public IStatusKeeper StatusKeeper { get; set; }

        [Import]
        public NetworkAgent NetworkAgent { get; set; }

        private static readonly ILog Log = LogManager.GetLogger("WorkflowAgent");

        public void Start()
        {
            _agent = Agent<WorkflowState>.Start(inbox =>
            {
                Action loop = null;
                loop = () =>
                {
                    var message = inbox.Receive();
                    var process = message.Then(Process, inbox.CancellationToken);                        
                    inbox.LoopAsync(process,loop,ex=>
                            Log.ErrorFormat("[ERROR] Synch for {0}:\r{1}", message.Result.FileName, ex));
                };
                loop();
            });
        }

        private Task<object> Process(WorkflowState state)
        {
            var accountInfo = state.AccountInfo;
            using (log4net.ThreadContext.Stacks["Workflow"].Push("Process"))
            {
                if (Log.IsDebugEnabled) Log.DebugFormat("State {0} {1} {2}", state.FileName,state.Status,state.TriggeringChange);

                if (state.Skip)
                {
                    if (Log.IsDebugEnabled) Log.DebugFormat("Skipping {0}",state.FileName);
                    
                    return CompletedTask<object>.Default;
                }
                string path = state.Path.ToLower();

                //Bypass deleted files, unless the status is Deleted
                if (!File.Exists(path) && state.Status != FileStatus.Deleted)
                {
                    state.Skip = true;
                    this.StatusKeeper.ClearFileStatus(path);
                    
                    if (Log.IsDebugEnabled) Log.DebugFormat("Skipped missing {0}", state.FileName);

                    return CompletedTask<object>.Default;
                }

                var fileState = FileState.FindByFilePath(path);
                var info = new FileInfo(path);


                switch (state.Status)
                {
                    case FileStatus.Created:
                    case FileStatus.Modified:
                        NetworkAgent.Post(new CloudUploadAction(accountInfo,info, fileState, accountInfo.BlockSize,
                            accountInfo.BlockHash));
                        break;
                    case FileStatus.Deleted:                       
                        NetworkAgent.Post(new CloudDeleteAction(accountInfo,info, fileState));
                        break;
                    case FileStatus.Renamed:
                        NetworkAgent.Post(new CloudMoveAction(accountInfo,CloudActionType.RenameCloud, new FileInfo(state.OldPath),
                                                              new FileInfo(state.Path)));
                        break;
                }

                return CompletedTask<object>.Default;
            }
        }


        //Starts interrupted files for a specific account
        public void RestartInterruptedFiles(AccountInfo accountInfo)
        {
            
            StatusNotification.NotifyChange("Restart processing interrupted files", TraceLevel.Verbose);

            using (log4net.ThreadContext.Stacks["Workflow"].Push("Restart"))
            {
                if (Log.IsDebugEnabled)
                    Log.Debug("Starting interrupted files");

                var cachePath = Path.Combine(accountInfo.AccountPath, FolderConstants.CacheFolder)
                    .ToLower();



                var account = accountInfo;
                var pendingEntries = from state in FileState.Queryable
                                     where state.FileStatus != FileStatus.Unchanged &&
                                           !state.FilePath.StartsWith(cachePath) &&
                                           !state.FilePath.EndsWith(".ignore") &&
                                           state.FilePath.StartsWith(account.AccountPath)
                                     select state;
                var pendingStates = new List<WorkflowState>();
                foreach (var state in pendingEntries)
                {
                    pendingStates.Add(new WorkflowState(account, state));
                }
                if (Log.IsDebugEnabled)
                    Log.DebugFormat("Found {0} interrupted files", pendingStates.Count);


                foreach (var entry in pendingStates)
                {
                    //Remove invalid state            
                    if (Directory.Exists(entry.Path))
                    {
                        Debug.Assert(false, "State has path instead of file", entry.Path);
                        StatusKeeper.ClearFileStatus(entry.Path);
                        return;
                    }
                    else
                        Post(entry);
                }
            }
        }



        public void Post(WorkflowState workflowState)
        {
            if (Log.IsDebugEnabled)
                Log.DebugFormat("Posted {0} {1} {2}", workflowState.Path, workflowState.Status, workflowState.TriggeringChange);

            //Remove invalid state            
            Debug.Assert(!Directory.Exists(workflowState.Path), "State has path instead of file", workflowState.Path);

            Debug.Assert(workflowState.Path.StartsWith(workflowState.AccountInfo.AccountPath, StringComparison.InvariantCultureIgnoreCase), "File from wrong account posted");

            _agent.Post(workflowState);
        }     

    }
}